What is "bel-imperia"

Bel-imperia is a character in Thomas Kyd’s The Spanish Tragedy. She is the daughter of the Duke of Castile, the sister of Lorenzo, and the lover of the dead Don Andrea. Throughout the play, Bel-imperia attempts to avenge the death of Don Andrea. She begins by feigning a relationship with Horatio to “spite the prince that wrought his end”, then joins forces with Hieronimo to eventually murder Balthazar and complete her revenge mission. However, critics view Bel-imperia in various roles based on her actions throughout the play.